1. Technical Field
The invention relates to assemblies for eliminating excess slack in cable casings and in particular to an assembly which adjusts the casing of a cable which extends between and operatively connects a pair of movable members. More particularly, the invention relates to a locking device for such assemblies which prevents overadjustment of the casing of a cable which circuitously extends between and operatively connects a temperature control module lever and a bulkhead door in a vehicle.
2. Background Information
All types of vehicles having enclosed passenger compartments, including automobiles, trucks, vans and mini-vans, continue to grow in popularity with the number of these vehicles predicted to increase in the future. Vehicle manufacturers, recognizing this ever-growing market, are continually striving to improve their products. These improvements include on-board computers for regulating and monitoring engine performance, improved aerodynamic design for better gas mileage and aesthetic appearance, interior upholstery which rivals that found in the living rooms of many homes, and even computers which calculate and display by LEDs on the dashboard everything from gas mileage to the preferred route for a trip. Despite such advances, manufacturers have been unable to satisfactorily solve the problem of forward firewall or bulkhead doors which improperly open and close upon manual adjustment of control levers for regulating the environment in the passenger compartment.
Most vehicles have a control module mounted in the dashboard for regulating the temperature within the passenger compartment. Other functions such as venting and defrosting of the vehicle windows also are controlled by manual adjustment of the module levers. The levers are connected by cables to the bulkhead doors which are movably mounted for opening and closing apertures formed in the bulkhead.
For example, in many automobiles one of the levers of the control module is moved to the "hot" position for opening a door on the bulkhead and permitting heat to be blown into the passenger compartment during cold weather. As the lever is moved from the "cold" to "hot" position, the cable extending between the lever and door is displaced in the direction of the lever, and the door is pulled to the open position. When the lever is returned to the "cold" position, the cable is displaced in the direction of the door and the door is pushed to the closed position.
Problems occur because the cable is slideably mounted in a casing which typically follows a circuitous path between the control module and door. The casing is required for guiding the cable along its circuitous path. In most vehicles, the cable casing is mounted at its ends adjacent to the door and control module lever, and when the cable is displaced the casing ends are forced against their mounting members if any excess slack is present in the casing. This excess slack cannot be relieved because the casing ends are immovable. Thus, the cable follows the circuitous path of the casing and because of the excess slack in the casing, the cable does not achieve the proper displacement or linear travel required for opening the bulkhead door. Also, the possibility of failure of the mounting members for the casing ends is increased due to the pressure exerted on the casing ends by the compressed casing. A similar problem occurs when an attempt is made to close the door, in that adequate displacement of the cable toward the door is not achieved because the cable again follows the circuitous path of the excessively slackened casing.
Therefore, it is apparent that excess slack in the cable casing prevents proper environment control within the vehicle passenger compartment. The operator of the vehicle often is confused because the expected position of the bulkhead door is not achieved when the control module lever is adjusted. Thus, although the lever may be positioned at full "hot", which indicates that the door is completely open, the actual position of the door may indeed only be half open.
It also should be noted that the phenomenon of excess slack in a casing for a cable extending in a circuitous path between two movable members occurs in applications other than for vehicles. For example, the same problems are common in the cable casing which extends between the control lever and the throttle of a lawn mower engine.
Attempts to solve such problems are well-known in the art and include such prior art devices as a turnbuckle connected to the cable casing, the mounting of a spring clip on the door end of the cable which is operatively connected to the control lever, and the use of a Bowden wire. However, many of these prior art devices require time-consuming installation and manual adjustment.
Known prior art assemblies include quick-connect fittings of the type used with pneumatic and hydraulic pressure system tubing and the like, and instant push-in tube fittings of the type which comprise a main lightweight body, an O-ring fluid seal and a plastic collet having stainless steel teeth.
The particular cable casing adjustment assembly of Pat. No. 4,892,003 which is assigned to the same assignee as the present application, satisfactorily solves most of the above-described problems in an economical and efficient manner.
The modified assembly shown and described herein solves the above-described problems in addition to other problems which occur in certain applications. More particularly, in many applications, a cable casing must traverse an unusually long and circuitous path to operatively connect the control lever and the bulkhead door, which can cause the problems set forth below.
The component of the adjustment assembly of the above-referenced patent application which allows adjustment of the casing in a first direction and prevents movement of the casing in a second direction opposite to the first direction after adjustment, preferably is a flat ring having a plurality of circumferentially spaced, generally radially inwardly extending gripping tangs inclined in the first direction. In normal applications, where the casing path is not unusually long and circuitous, the tangs are resilient enough to allow movement of the casing through the tang ring in the first direction during adjustment, yet rigid enough to prevent unintended post-adjustment movement of the casing through the tang ring in the first direction resulting in overadjustment of the casing which can prevent proper operation of the bulkhead door. Such unintended movement can be caused by vehicle vibrations, movement of the bulkhead door past its fully open position caused by excessive air flow past the door, etc.
The rigidity of the tangs necessary to counteract such potential unintended forces requires that a certain predetermined force be exerted on the casing by manual adjustment of the control module lever in a predetermined direction, in order to move the casing past the tangs and in the first direction to the adjustment position. Where the path of a casing is unusually long and circuitous, it becomes difficult to exert enough force on the casing by manual movement of the lever to move the casing through the tang ring. Thus, the tangs must be formed of a less rigid material which, while not affecting the ability of the tangs to resist casing movement in the second direction, does allow the inadvertant forces such as vehicle vibration, to force the casing past the tangs and into an overadjusted position. The present invention solves this overadjustment problem by adding a mechanical lock to the assembly of application Pat. No. 186,570.
There is no assembly and method for the adjustment of a cable casing of which I am aware, other than my present invention, which is quickly and easily installed and adjusted on a vehicle on a production line at a vehicle assembly plant, which will provide for removal of excess slack in an unusually long and circuitous cable casing and subsequently prevent overadjustment of the casing, and which is rugged and relatively inexpensive to manufacture and install.